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Ch. 3 - Polynomial and Rational Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
4장, 문제 19

Match each statement with its corresponding graph in choices A–D. In each case, k > 0. y varies directly as the second power of x. (y=kx2)
Four graphs labeled A to D showing different curves of y versus x, illustrating variations of y = kx² with k > 0.

검증된 단계별 안내
1
Identify the type of variation described: "y varies directly as the second power of x" means the relationship can be written as \(y = kx^{2}\), where \(k > 0\).
Recognize the shape of the graph for \(y = kx^{2}\): Since \(k\) is positive and the power of \(x\) is 2, the graph is a parabola opening upwards.
Recall key features of the parabola \(y = kx^{2}\): It is symmetric about the y-axis, passes through the origin (0,0), and as \(|x|\) increases, \(y\) increases quadratically.
Compare the given graph choices A–D to these characteristics: Look for the graph that shows a U-shaped curve opening upwards, symmetric about the y-axis, and passing through the origin.
Match the statement \(y = kx^{2}\) with the graph that fits these features, confirming it represents direct variation with the second power of \(x\).

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Direct Variation

Direct variation describes a relationship where one variable is equal to a constant multiplied by another variable raised to a power. In this case, y varies directly as x squared, meaning y = kx², where k is a positive constant. This implies that as x increases, y changes proportionally to the square of x.
추천 영상:
02:44
Maximum Turning Points of a Polynomial Function

Quadratic Functions and Their Graphs

A quadratic function has the form y = ax² + bx + c, and its graph is a parabola. For y = kx² with k > 0, the parabola opens upward and is symmetric about the y-axis. Understanding the shape and orientation of this graph helps in matching the equation to its correct graph.
추천 영상:
5:26
Graphs of Logarithmic Functions

Effect of the Constant k on the Graph

The constant k in y = kx² affects the steepness or width of the parabola. When k > 0, the parabola opens upward; larger values of k make the parabola narrower, while smaller values make it wider. Recognizing how k influences the graph aids in identifying the correct match among given options.
추천 영상:
6:16
Transformations of Exponential Graphs